WCDMA uplink HARQ operation during the reconfiguration of the TTI length

Abstract

A method for minimizing the loss of data and ensuring that large delays do not occur during reconfigurations of an uplink transmission time interval (TTI) length of a WCDMA High Speed Packet Uplink Access (HSUPA) air interface, wherein the reconfiguration of an uplink TTI length is delayed until all pending retransmissions are successfully transmitted or until the maximum number of transmissions is reached. The transmission of new packets during this time period is prevented. However, pending retransmissions are allowed to occur. After the UE has received an ACK/NACK for each HARQ process, or until the specific maximum number of re-transmissions is reached, the UE starts transmitting with a new uplink TTI length.

1. A method comprising:
 transmitting first data packets at a first uplink transmission time interval (TTI) length from a user device to a base station; 
 in response to the user device receiving a reconfiguration command from a serving radio network controller, preventing transmission of any data packets from the user device for a predetermined time interval, wherein the predetermined time interval is a duration of time that is based on a number of hybrid automatic repeat request (HARQ) processes currently running; and 
 after the predetermined time interval, transmitting second data packets at a second uplink TTI length from the user device to the base station, where the second uplink TTI length is different from the first uplink TTI length. 
 
     
     
       2. The method of  claim 1 , wherein the first uplink TTI length is 2 ms and the second uplink TTI length is 10 ms. 
     
     
       3. The method of  claim 1 , further comprising initiating, in response to receiving the reconfiguration command, a synchronous reconfiguration of the uplink TTI length of the user device at a connection frame number at which the reconfiguration is to occur. 
     
     
       4. The method of  claim 1 , wherein the predetermined time interval is a time period in which a previously established maximum number of transmissions with the first uplink TTI length occurs. 
     
     
       5. The method of  claim 1 , wherein the predetermined time interval is at least one of a time period in which all retransmitted first data packets have been positively acknowledged or a time period in which a previously established maximum number of first data packet transmissions is reached. 
     
     
       6. The method of  claim 1 , further comprising:
 retransmitting unsuccessfully received first data packets as second data packets using the second uplink TTI length. 
 
     
     
       7. The method of  claim 6 , further comprising:
 clearing hybrid automatic repeat request (HARQ) buffers of the base station for HARQ processes having pending retransmissions of first data packets. 
 
     
     
       8. The method of  claim 7 , wherein clearing is performed subsequent to receipt of a last indication of receipt for the first data packets. 
     
     
       9. The method of  claim 1 , performed as a result of executing program instructions stored in a memory medium of the user equipment. 
     
     
       10. The method of  claim 1 , further comprising: receiving, by the user device, acknowledgements from the base station that indicate receipt or non-receipt of the first data packets. 
     
     
       11. The method of  claim 10 , wherein an indication of receipt of a second data packet is received at the user device subsequent to receipt of an acknowledgement for a last first data packet. 
     
     
       12. The method of  claim 1 , where the reconfiguration command reconfigures the uplink TTI length from the first uplink TTI length to the second uplink TTI length. 
     
     
       13. The method of  claim 1 , where the first uplink TTI length is 10 ms and the second uplink TTI length is 2 ms. 
     
     
       14. An apparatus, comprising:
 a transmitter configurable to transmit first data packets at a first uplink transmission time interval (TTI) length to a base station; 
 a receiver configurable to receive a reconfiguration command from a serving radio network controller; and 
 a processor configurable, in response to receipt of the reconfiguration command, to prevent transmission of any data packets from the apparatus for a predetermined time interval, wherein the predetermined time interval is a duration of time that is based on a number of hybrid automatic repeat request (HARQ) processes currently running, said processor further configurable to enable, after the predetermined time interval, transmission of second data packets at a second uplink TTI length from the apparatus to the base station, where the second uplink TTI length is different from the first uplink TTI length. 
 
     
     
       15. The apparatus of  claim 14 , where in response to receipt of the reconfiguration command said processor is further configurable to initiate a synchronous reconfiguration of the uplink TTI length at a connection frame number at which the reconfiguration is to occur. 
     
     
       16. The apparatus of  claim 14 , where the first uplink TTI length is 10 ms and the second uplink TTI length is 2 ms. 
     
     
       17. The apparatus of  claim 14 , where the receiver is further configurable to receive at least acknowledgements from the base station that indicate receipt or non-receipt of the first data packets and where an indication of receipt of a second data packet is received subsequent to receipt of an acknowledgement for a last first data packet. 
     
     
       18. The apparatus of  claim 14 , where the predetermined time interval is a time period in which a previously established maximum number of transmissions with the first uplink TTI length occurs. 
     
     
       19. The apparatus of  claim 14 , where the predetermined time interval is at least one of a time period in which all retransmitted first data packets have been positively acknowledged or a time period in which a previously established maximum number of first data packet transmissions is reached. 
     
     
       20. The apparatus of  claim 14 , said processor further configurable to retransmit unsuccessfully received first data packets as second data packets using the second uplink TTI length. 
     
     
       21. The apparatus of  claim 14 , embodied as a user equipment operable with a high speed packet uplink access air interface. 
     
     
       22. The apparatus of  claim 14 , where the reconfiguration command reconfigures the uplink TTI length from the first uplink TTI length to the second uplink TTI length.